v3 -> v4: - Rename the syscall: getumask becomes umask2.
- Add flags parameter, with one flag (UMASK_GET_MASK). - Expand the rationale for this change in the first commit message. - Add a selftest. - Retest everything. -------------------- It's not possible to read the process umask without also modifying it, which is what umask(2) does. A library cannot read umask safely, especially if the main program might be multithreaded. This patch series adds a new system call "umask2". This adds a flags parameter. Specifying flags=UMASK_GET_MASK allows the umask of the current process to be read without modifying it. This leaves open the possibility in future of adding a per-thread umask, set or read with other flags. This is not implemented. Another approach to this has been attempted before, adding something to /proc, although it didn't go anywhere. See: http://comments.gmane.org/gmane.linux.kernel/1292109 Another way to solve this would be to add a thread-safe getumask to glibc. Since glibc could own the mutex, this would permit libraries linked to this glibc to read umask safely. I should also note that man-pages documents getumask(3), but no version of glibc has ever implemented it. Rich.
